Abstract: This paper described the whole process of Wechat R&D that is of special relevance to open services innovation. Not only dynamic evolution but also the synergy mechanisms have been distinguished. This paper defined the dynamic evolution of Wechat in terms of its vertical development from user involvement innovation phase, external participation innovation phase, platform innovation phase to multi-platform innovation phase. The operation team fulfilled its innovation objectives with different strategies, such as user collaboration, external resources utilization, open platform strategy and cross-border cooperation. Based on the analysis of dynamic evolution, the synergy mechanisms of open services innovation on the basis of innovative environment, the interactive network of innovative sources and business platform is developed. This study found that the platform innovation of interaction between Wechat team, external organizations and users is the core and essence of open services innovation.